\begin{tikzpicture}
\node (a) at (0,0){$\circledtext{i}   \stackrel{\mathbf{a}}{\longrightarrow}\circledtext{j}$};
\node (b) at ([xshift=7em,yshift=-2em]a.south){$L(F A)=\left\{x \mid(i \stackrel{x}{\Rightarrow} j), x \in \Sigma^{*}, i \in S, j \in F\right\}$};
\end{tikzpicture}